Agitator for mixing high viscosity materials



July 14, 1970 c. A. CROSS 3,520,519

AGITATOR FOR MIXING HIGH VISCOSITY MATERIALS Filed Sept. 50, 1968 AIR COMPRESSOR I I I 18 I 18.9 v6 INVENTOR.

CHARLES A. CROSS BY mum ATTORNEY United States Patent 3,520,519 AGITATOR FOR MIXING HIGH VISCOSITY MATERIALS Charles A. Cross, South Toms River, N.J., assignor to the United States of America as represented by the Secretary of the Navy Filed Sept. 30, 1968, Ser. No. 763,737 Int. Cl. B01f 7/16 US. Cl. 259-122 10 Claims ABSTRACT OF THE DISCLOSURE A rotary agitator having two sets of lifting blades and two sets of mixing blades radially disposed and axially aligned along the rotational axis of a shaft member for mixing and liquifying materials of high viscosity.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to mixing apparatus and more particularly to a rotatable air-powered agitator for mixing the high viscosity ingredients of a nonskid composition that is used to coat the landing surface of portable airfield matting.

In any landand-sea military operation, the quick assembly of a temporary airfield which can be erected near a battle zone or some other hard to get at position provides ground units with the added advantage of continuous air support. The various branches of the armed forces consequently have been trying to develop various types of rapidly constructed expeditionary airfields for a period of over two decades now.

Presently, expeditionary airfields, such as the SATS (Short Airfield for Tactical Support) developed by the Navy, are constructed of strong, lightweight prefabricated aluminum surface matting. During manufacture, the airfield matting is covered with a nonskid coating composition to improve traction and prevent the rapid deterioration and wear of the matting surface to an extent that would effect the safety of aircraft catapult and arresting operations. After prolonged use, the nonskid coating wears off and must be repaired and replaced before operation of the airfield can safely commence.

The nonskid coating consists of a nonskid compound and accelerator therefor, for example, such as the Durapox Emergency Nonskid Repair Kit, manufactured by Palmer Products, Incorporated. Each 45 gallons of Durapox compound is contained in a storage drum with an approximate capacity of 55 gallons; 5 gallons of an accelerator or hardener is added to each 45 gallons of compound for a proper mixture. To realize proper cure of the nonskid coating, it is necessary that the required amount of accelerator and nonskid compound be mixed together and agitated to a heavy liquid consistency prior to application. In order to insure the proper effectiveness of the coating, it must be applied to the runway surface in a smooth, uniform thickness, preferably by immediately air spraying the mixture onto the matting surfaces to make certain that the abrasives within the mixture stay in suspension. However, heretofore, because the nonskid coating compounds are heavy, sand-based, concrete like mixtures, the mixers, agitators and power means suggested and known in the industry were unable to properly mix and liquify a drum full of material. Also, none were portable or adequate to do large batch mixing under field conditions. As a result, the nonskid compound that was mixed and prepared at the field site could not be sprayed on but had to be brushed or mopped on, Mopping proved to be a laborious procedure which also provided a poor, non-uniform coated surface on the airfield matting.

It is therefore an object of the present invention to provide a novel and improved portable agitator for use indoors or outdoors under field conditions to mix and liquify viscous compounds.

It is a further object of the present invention to provide a novel and improved mixing apparatus capable of liquifying nonskid mat repair coating compound in a relatively short period of time.

It is another object of the present invention to provide a rotary agitator for mixing nonskid materials so that they may be successfully sprayed onto a solid surface.

A still further object of the present invention is to provide a novel and improved mixing agitator and associated apparatus for liquifying nonskid coating compound which is relatively simple in construction and operation and yet highly reliable in use.

Other objects, advantages and novel features of the inventon will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing wherein:

FIG. 1 of the drawing is generally a front elevational view of a preferred agitator constructed according to this invention with associated apparatus shown partly in section and partly in diagrammatic form; and

FIG. 2 of the drawing is a front elevational View of a portion of the agitator of FIG. 1 with the shaft member rotated clockwise through Referring now to the details of the drawing, wherein like reference numerals apply to like parts throughout, it will be seen that the present invention comprises a r0- tary agitator or mixing paddle 10 which includes four sets of axially aligned impeller blades 11-14, each set of blades radially disposed on a rotatable shaft member 15. The first set of impeller blades 11 include a pair of flat lifting blades which are diametrically positioned at acute blade angles, preferably between 55 and 60. The blades 11 have a tubular sleeve member 16 attached to or formed integral with the leading edges thereof. The sleeve members 16 have internally threaded surfaces provided to engage a pair of tubular rod members 17 having complementary threaded external surfaces which project radially from the end of the shaft 15. The blades 11 are positioned on the rod members 17 so that a small separation remains between the shaft member 15 and the inner end of the blades 11. The blades 11 are generally rectangular in shape and have a circular aperture 18 located in the center of each of the blades, for a reason which will become more apparent hereinafter.

The second set of impeller blades 12 consist of two pairs of flat mixing blades 19 and 20, respectivel radially disposed on the shaft member 15 and positioned above and radially perpendicular to the blades 11. The blades 19 and 20 are generally rectangular in shape with the blade pair 19 having rounded tips and each pair positioned at an acute blade angle, the blades 19 preferably adjusted between 13 and 18 and the blades 20 preferably between 83 and 88. A portion of the leading edges of the blades 19 are positioned to contact the corner of the blades 11 formed by the trailing edge and the inner end of the respective blades. The blades 20 are positioned to have their leading edges in contact with the faces of the blades 19 and lying along the center line of the long axis thereof. The blades 20 also preferably have three circular apertures 21 located thereon, one in the center of each blade and one symmetrically located on each side thereof, for a reason which will become more apparent hereinafter.

The third set of impeller blades 13 include a pair of fiat lifting blades which are diametrically positioned at acute blade angles, preferably between 43 and 48. The blades 13 are generally rectangular in shape having rounded tips and positioned above and radially perpendicular to the second set of impeller blades 12.

The fourth set of impeller blades 14 include a pair of flat mixing blades which are diametrically positioned at a blade angle of 90, that is, parallel to the rotational axis of the shaft member 15. The blades 14 are generally rectangular in shape and positioned above and radially perpendicular to the third set of impeller blades 13.

It is to be noted that the impeller blades 11-14 may be constructed from stamped or rolled steel or any other suitable conventional metal having similar properties. Also, the impeller blades 12-14 may be mounted on the shaft member 15 by welding them into position on the shaft or by forming the blades around a circular hub designed to fit around the shaft member 15, or by any other suitable means which will provide permanence and prevent movement of the blades from their set positions.

In accordance with the present invention, the shaft member 15 is mounted on a storage drum cover 22 having a plurality of screw or locking means 23 provided around the periphery of the portion overlapping the top edge of the storage drum 24 containing the nonskid coating compound. The cover 22 has a circular opening 25 located in the center thereof with a tubular sleeve member 26 communicating with the opening 25 and extending down into the interior of the storage drum 24. The shaft member 15 is inserted through the opening 25 and extended through the sleeve member 26 which serves as a lateral support for the free rotation of the shaft 15 within the storage drum 24. As it is desirable that the agitator be portable and capable of either indoor or outdoor use, the shaft member is preferably connected to a lightweight airpowered motor 27 by the coupling means 28. An air compressor 29 which is preferably of the gasoline driven rotary type which may be integrally mounted on a truck chassis is connected to the motor 27 through the air line 30 to drive the motor and rotate the agitator 10.

In operation of the embodiment described above, the agitator 10 is rotated about the vertical axis of the storage drum 24 whereby the placement and angle of the impeller blades 11 moves the viscous material to be mixed upward from the bottom of the storage drum 24 into the path of the set of impeller blades 12 above it which partially dissolves and disperses the nonskid material upward into the path of the second pair of lifting blades 13 that in turn deliver the material to the final pair of mixing blades 14. The action of the rotating blades initiates a continuous flow path for the nonskid material from the bottom of the storage drum 24 to the top, principally through the center portion of the drum adjacent the shaft member 15, and down along the outer wall area of the drum. The circular apertures 18 and 21 of the blades 11 and 20, respectively, aid in relieving some of the resistance to rotary motion caused by the nonskid material itself, due to the concrete-like consistency of the mixture. The apertures 18 and 21 allow a portion of the material to pass through the respective blade faces instead of having all of the material being lifted by the blades, thereby enabling the system to utilize a motor 27 whose size and torque requirement is comparatively small.

It has been found in actual practice that fifteen minutes are required using the above described apparatus to thoroughly mix the Durapox Nonskid Compound contained in a standard 55 gallon metal storage drum so that the mixture is sufiiciently liquified to enable it to be sprayed onto the matting surface. The dimensions of the individual blades for optimum mixing performance are preferably as follows: The first set of impeller blades 11 are approximately 3 inches wide by 8 inches long with the circular aperture 18 having a diameter of approximately one inch; the blades 19 of the second set 12 are approximately 4 inches wide by 10 inches long and the blades of the second set 12 are approximately 3 inches wide by 8 inches long with the circular apertures 21 having diameters of approximately of an inch; the third set of impeller blades 13 are approximately 3 inches wide by 9 inches long; and the fourth set of impeller blades 14 are 2 inches wide by 3 inches long. By employing the abovementioned preferred blade dimensions, and an agitator rotational speed of not more than 180 revolutions-perminute, it was found that the compound may be mixed for approximately 10 minutes prior to adding the accelerator and then continued for 5 minutes after adding the accelerator for each storage drum of Durapox compound to be used.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A rotary agitator for mixing high viscosity, nonskid coating compounds for airfield matting, comprising:

(a) a rotatable shaft;

(b) a first set of impeller blades radially disposed at the end of the shaft for rotation therewith having a pair of diametrically positioned, flat lifting blades secured at acute blade angles so that the compound to be mixed is pushed upward during rotation of the shaft;

(c) a second set of impeller blades radially disposed on the shaft above the first set of blades having two pairs of diametrically positioned, flat mixing blades secured at acute blade angles for mixing and liquifying the compound;

(d) a third set of impeller blades radially disposed on the shaft above the second set of blades having a pair of diametrically positioned, fiat lifting blades secured at acute blade angles so that the compound to be mixed is pushed upward;

(e) and a fourth set of impeller blades radially disposed on the shaft above the third set of blades having a pair of diametrically positioned, flat mixing blades secured at a blade angle of for mixing and liquifying the compound.

2. A rotary agitator substantially as described in claim 1, wherein:

(a) the first and third set of impeller blades extend in radially parallel directions;

(b) and the second and fourth set of impeller blades extend in radially parallel directions, perpendicular to said first and third set of impeller blades.

3. A rotary agitator substantially as described in claim 2, wherein:

(a) the first set of impeller blades are secured at blade angles of about 55 to 60, the chord line of each blade of said first set of blades extending in opposite directions from the axis of rotation;

(b) the second set of impeller blades having the first pair of blades secured at blade angles of about 13 to 18 and the second pair of blades secured at blade angles of about 83 to 88, the chord line of each blade of said first and second pair of blades extending in opposite directions from the axis of rotation, respectively;

(c) and the third set of impeller blades secured at blade angles of about 43 to 48, the chord line of each blade of said third set of blades extending in opposite directions from the axis of rotation.

4. A rotary agitator substantially as described in claim 3, wherein:

(a) the first set of impeller blades are generally rectangular in shape and have a blade area of approximately four times the area of said fourth set of impeller blades;

(b) the second set of impeller blades are generally rectangular in shape with the first pair of blades having rounded tips and a blade area of approximately six times the area of said fourth set of impeller blades and the second pair of blades having a blade area of approximately four times the area of said fourth set;

(c) the third set of impeller blades are generally rectangular in shape with rounded tips and a blade area of approximately four times the area of said fourth set of impeller blades;

(d) and the fourth set of impeller blades are generally rectangular in shape.

5. A rotary agitator substantially as decribed in claim 4, wherein each blade of the fourth set of impeller blades has a blade area of approximately 6 square inches.

6. A rotary agitator substantially as described in claim 4, wherein:

(a) the first set of impeller blades has a circular aperture having a diameter of approximately 1 inch located in the center of each blade;

(b) and the second pair of blades of said second set of impeller blades each have three circular apertures having a diameter of approximately /1 of an inch located at the center of each blade and symmetric on each side thereof, whereby said apertures decrease the resistance of the blades to rotary motion through the compound.

7. A rotary agitator substantially as described in claim 6, wherein:

(a) a pair of diametrically positioned, externally threaded rods are radially disposed at the end of the shaft;

(b) and a tubular sleeve having a complementary threaded inner surface is attached to the leading edge of each of the blades of said first set of impeller blades, said tubular sleeves adapted to engage the tubular rods so that said first set of blades may be supported and positioned thereon leaving a small separation between said first set of blades and said shaft.

8. A rotary agitator substantially as described in claim 7, wherein:

(a) the first pair of blades of said second set of impeller blades have their leading edges in intimate contact with the corner formed by the trailing edge and the inner end of the blades of said first set of impeller blades, respectively;

(b) and the second pair of blades of said second set have their leading edges in intimate contact with the blade faces of said first pair of blades, respectively, the leading edges of said second pair lying along the center line of the long axis of said first pair of blades.

9. A rotary agitator substantially as described in claim 8, wherein:

(a) the shaft is rotated by an air-powered motor;

(b) and the shaft is mounted on a storage drum cover, said cover having a circular opening located in the center thereof and a tubular sleeve communicating with said opening to provide lateral support for the shaft when it is extended through the sleeve and the opening in preparation for vertical mixing operation within a storage drum.

10. A rotary agitator substantially as described in claim 9, wherein:

(a) said storage drum cover is constructed to fit a standard gallon metal drum;

(b) and wherein each of the first set of blades are approximately 3 inches Wide by 8 inches long, each of the first pair of blades of said second set are approximately 4 inches wide by 10 inches long, each of the second pair of blades of said second set are approximately 3 inches wide by 8 inches long, each of the third set of blades are approximately 3 inches wide by 9 inches long and each of the fourth set of blades are approximately 2 inches wide by 3 inches long.

References Cited UNITED STATES PATENTS 2,269,736 1/1942 Rogers 259-422 X 2,898,094 8/1959 ONeill 259-122 X 3,132,850 5/1964 Puchalski 259-122 X 3,166,303 1/1965 Chapman 259- 3,295,836 1/1967 Langella 259-122 ROBERT W. JENKINS, Primary Examiner 

